.

teensy3/mk20dx128.c

 	// configure USB for 48 MHz clock
 #if F_CPU == 144000000
 	SIM_CLKDIV2 = SIM_CLKDIV2_USBDIV(2); // USB = 144 MHz PLL / 3
-#elif F_CPU == 120000000
-	SIM_CLKDIV2 = SIM_CLKDIV2_USBDIV(4) | SIM_CLKDIV2_USBFRAC; // USB = 120 MHz PLL / 2.5
 #else
-    SIM_CLKDIV2 = SIM_CLKDIV2_USBDIV(1); // USB = 96 MHz PLL / 2
+	SIM_CLKDIV2 = SIM_CLKDIV2_USBDIV(1); // USB = 96 MHz PLL / 2
 #endif	
 	// USB uses PLL clock, trace is CPU clock, CLKOUT=OSCERCLK0
 	SIM_SOPT2 = SIM_SOPT2_USBSRC | SIM_SOPT2_PLLFLLSEL | SIM_SOPT2_TRACECLKSEL | SIM_SOPT2_CLKOUTSEL(6);